In recent years, certain high performance bicycles have included hydraulic disc brakes. Hydraulic disc brake systems typically include a caliper housing, a first movable brake pad and a second fixed or movable brake pad. The movable brake pad is typically attached to a piston that is movable in response to fluid pressure applied via a hydraulic fluid conduit in the caliper housing. The brake pads are positioned on either side of a rotor, which is attached to the front or rear wheel of a bicycle. Upon the application of fluid pressure to the piston or pistons, the brake pads come into contact with the rotor, thereby applying frictional resistance and causing the bicycle to slow down or stop.
Hydraulic disc brake systems for bicycles are typically actuated by a brake lever attached to a bicycle handlebar. They also typically include a master piston in a master cylinder which is actuated by the brake lever. The master cylinder contains a hydraulic fluid and is in fluid communication with the disc brake caliper via a fluid conduit. The brake pads are typically spaced apart from the rotor by a predetermined gap. As the lever is contracted towards the handlebar, the master piston moves, thereby forcing liquid out of the master cylinder and into a conduit connected to the caliper housing. The movement of fluid into the caliper housing causes the pistons to move, eventually bringing the brake pads into contact with the rotor. Once the brake pads contact the rotor, they provide frictional resistance which can be increased by further operation of the lever. At this point, the caliper housing is fully pressurized, and further operation of the lever increases the system hydraulic pressure and frictional resistance applied to the rotor.
Some of the hydraulic fluid in the system is contained in a fluid reservoir that is often located on the brake lever assembly at a location where the reservoir and its housing could be damaged if a rider was to have an accident.
Accordingly, a need exists for a hydraulic disc brake lever system that addresses the foregoing problems.